Enter the "Extras" menu, select the "Promotional Codes" option, then enter one of the following codes to activate the corresponding cheat function:

Eye Of Ra ASE

Enter "EYEOFRA" as a code to unlock Eye Of Ra ASE.

Golden Destroyer Armor in Multiplayer mode

Enter "14KARMOR" as a code to unlock the Golden Destroyer Armor in Multiplayer mode.

Dark Star and armor upgrades

Walk in a circle in the main room of Atlantis with ASE. Scan all possible items to get the Dark Star and armor upgrades.

Hive Cannon

From the Atlantis hub program, use the Conduit to go to Oxford University. When you arrive, look to the right to see a rock pillar. Jump to it, then use the ASE on the scannable object in the middle to get the blueprints for the Hive Cannon.

Longer fire and invisibility time with AR-C Eclipse

When using the AR-C Eclipse (the gun that can turn you invisible), before turning invisible for getting past turrets or enemies, shoot the gun until it is almost overheated. Then, charge it up so you turn invisible. The gun will need time to cool down before lowering its temperature below zero. This will allow you to remain invisible for longer. This also applies to the shooting feature. If you need to shoot for long periods of time, turn invisible until the temperature is almost at its minimum, then start shooting. You will be able to keep firing for a longer time.

Easy "Green Ooze" achievement

Play the Washing D.C. level. Go to the trailer, and fall down the ladder to the sewer. Kill both mites in the room, then aim your reticule at the canister of Green Ooze with tiny footprints going into the sewer water.

Achievements

Successfully complete the indicated task to unlock the corresponding achievement:

1337 Status: Obtain Rank 45 in matchmaking.

Armor Piercing: Kill 35 Advancers.

Awesome Kill: Kill 3 opponents within 4 seconds of each other.

Back in Action!: Escape the gas chamber on the Trust Platform.

Blaster Kill: Kill 4 opponents within 4 seconds of each other.

Blindfolded Warrior: Kill an opponent while you are blinded by a Flash Grenade.

Bomb Squad: Disarm the weapon in D.C.

C2 Novice: Obtain Rank 5 in matchmaking.

Cartography: Discover all of the Conduit coordinates.

Competitive: Play in a game with a rival.

Conduit 2 Master: Earn every achievement.

Deconstruction: Kill 50 Fixers.

Defender: Finish round 2 of Invasion.

Detective: Complete 75% of the Data Log.

Die Alien Scum!: Finish round 4 of Invasion.

Engineering Bay: Obtain all of the weapon blueprints.

Enlightened: Complete 100% of the Data Log.

Exterminator: Kill 150 Drones.

Fresh Brewed: Crouch several times while standing near a wounded player in multiplayer.

Friendly: Play in a game with a friend.

Gaming Party: Play in a four player splitscreen game.

GimmeDaGold: Have 100,000 cr to your name.

He Came From Behind: Destroy all the shield turrets in China.

Heart in Darkness: Destroy the Drudge hearts beneath D.C.

Helping Hand: Help the Othu and the Free Drudge escape.

Ice Queen: Take Katarina's soul.

In the Name of Science!: Kill 50 Scientists.

Inquisitive: Complete 50% of the Data Log.

Invasion's Fun!: Finish round 3 of Invasion.

Just Bodies.: Finish round 5 of Invasion.

Kill Fest: Kill 10 opponents in a row without dying.

Killer Kill: Kill 5 opponents within 4 seconds of each other.

Killing Spree: Kill 3 opponents in a row without dying.

Learning the Ropes: Obtain Rank 15 in matchmaking.

Leviafun: Defeat the Leviathan.

Massacre: Kill 5 opponents in a row without dying.

Observer: Complete 25% of the Data Log.

Optimal Primer: Deal with the primers on the Trust Platform.

Over 9,000!: Gain enough power to take on Adams.

Powered Up: Collect all of the Progenitor Energy.

Pro Skills: in matchmaking, finish a free for all game in 1st place without using any suit upgrades.